>>33339667It's actually the one next to it in the middle that's more relevant.
This is clearly just a cloud designed to look like Dialga. There is one on the upper left like Palkia and in the upper right like Giratina. Just as Ho-oh and Lugia were in the original region images clouds.
However the one in the middle is randomly just there which could that IS hiding something. Probably not considering their recent design philosophy, but far more likely than cloudialga.